The need to store digital files, documents, pictures, images and other data continues to increase rapidly. In connection with the electronic storage of data, various data storage systems have been devised for the rapid and secure storage of large amounts of data. Such systems may include one or a plurality of storage devices that are used in a coordinated fashion. Systems in which data can be distributed across multiple storage devices such that data will not be irretrievably lost if one of the storage devices (or in some cases, more than one storage device) fails are also available. Systems that coordinate operation of a number of individual storage devices can also provide improved data access and/or storage times. Examples of systems that can provide such advantages can be found in the various RAID (redundant array of independent disks) levels that have been developed. Whether implemented using one or a plurality of storage devices, the storage provided by a data storage system can be treated as one or more storage volumes.
In order to facilitate the availability of desired data, it is often desirable to maintain different versions of a data storage volume. By maintaining different versions, disaster recovery is facilitated. For example, if a virus causes a current storage volume version to be lost or otherwise unusable, the system can be rolled back to an earlier version that does not include the file that introduced the virus. However, maintaining different versions of data storage volumes is expensive and inefficient, as it requires maintaining complete copies of each storage volume version. This problem is multiplied if a number of backup versions of a storage volume are maintained. In addition, once a different version of a storage volume is restored, it is often impossible to revert to another version, for example if the restored volume is determined to be less desirable than the storage volume previously applied. Also, a storage volume selected in connection with a restore operation is often not available immediately, and the ability to create additional versions of the storage volume may be impossible while rollback to the selected storage volume is being completed.